Add single glyph view in the lower section of Reference Fonts

[mrk-z]

Currently in the lower section of the Reference Font panel, all the imported reference fonts are displayed at once, and they are not clearly labeled, so it's a little difficult to see which font is which. Also the size of the font is controlled by a slider, so when resizing the panel/browser window, the designer needs to resize the fonts again, which is not very convenient.

It'd be great to have a "single glyph view", which only shows the current glyph in the selected font. The glyph should fill the width of the panel, and responds to re-sizing of the panel/browser window.

Meanwhile the "multi-font grid view" could be kept, since it could be useful when comparing different fonts. But they could be labeled with their font name, and also respond to the size of the panel/browser window. (Maybe an option to choose how many fonts in a row, but the overall width always fills the panel width.)

[mrk-z]

"single glyph view"